This invention relates to backplanes for electro-optic displays, and to processes for the formation of such backplanes. The backplanes of the present invention are especially, but not exclusively, intended for use with particle-based electrophoretic displays in which one or more types of electrically charged particles are suspended in a liquid and are moved through the liquid under the influence of an electric field to change the appearance of the display.
In some instances, a flexible display may be folded for portability and/or convenience of storage. If the display was simply folded in a book like fashion, it may be folded with a radius of curvature that is smaller than a minimum radius of curvature designed to prevent display breakage. To prevent such problem, various mechanisms, such as hinges and/or other structures, have been implemented to the bending portions of the display. For example Polymer Vision has disclosed a product Readius™ using one or more mechanical hinge mechanisms to facilitate the folding of the flexible display.
In another example, Japanese Patent Laid-Open Publication No. 2014-161009 discloses a flexible mobile terminal device configured to bend at various angles. The terminal device is proposed to include a folding portion for bending the device to a front surface or a rear upper position of a terminal device body. A flexible display mounted on an upper portion of the terminal device body can be bend to the front surface or a rear surface depending on a bending direction of the folding portion. The device further includes a sliding portion for causing one end of the flexible display to slide by a difference between degrees of compression/tension generated by a difference in extension rates of the folding portion and the flexible display during bending of the folding portion.
Both examples described above result in thick and heavy products. The Readius™ by Polymer Vision employs mechanical hinge mechanisms that are complex in structure and bulky in shape. The device of Japanese Patent Laid-Open Publication No. 2014-161009 has a bellows shape and the sliding portion takes labor to adjust, and the device is also complex and bulky.
An additional limitation of book-like flexible electro-optic displays of the prior art is that a portion of the flexible electro-optic display(s) may not assume a flattened position after repeated openings and closings. In particular, the fold area may become “wrinkly” making it difficult to read across the bended portion. In other devices, where the flexible display is allowed to “float” so that it can move with respect to the frame, the display may not flatten fully, or worse yet, it may move while the user is reading. The present invention addresses many of these issues and provides a foldable electro-optic display that is flexible, thin, and light-weight, and may be folded in a book-like fashion.